The innate immune system provides an immediate nonspecific response to invading pathogens. Communication among mucosal keratinocytes and with proximal immune cells is fundamental to such a response. The long-term goal of this project is to characterize cell-to-cell communication in oral tissues through connexin hemichannels and gap junctions in order to design new treatments for infection of mucosal tissues. Connexins are proteins that form cell-to-cell channels, which are concentrated within gap junctions. Cell-to-cell communication can be initiated by the opening of gap junction channels between cells. In addition, connexin hemichannels (undocked channels) can promote the transfer, release or uptake of cytosolic bioactive mediators - effectively providing for communication between cells via an extracellular pathway. These mediators could signal proximal epithelial and immune cells to the presence of invasive pathogens. However as P. gingivalis penetrates periodontal tissue, cell-to-cell communication controlling inflammation may become destructive. In preliminary experiments, we have shown that Porphyromonas gingivalis potentiates hemichannel opening in oral epithelial cells, an immediate response to fluid movement above the cells (mechanical stimulation), and oral keratinocytes express predominately connexin 43 (Cx43). We hypothesize, therefore, that P. gingivalis potentiates hemichannel opening in mucosal epithelial cells through TLRs, increasing inflammation and the severity of periodontal disease. To test this hypothesis we will: 1. Characterize the role of Cx43 in P. gingivalis potentiation of hemichannel and gap junction communication in gingival epithelial cells. 2. Determine whether hemichannel opening is a result of signaling from engagement of TLRs. 3. Show that Cx43 is involved in the progression [increasing severity] of periodontal disease using a mouse model of periodontitis. Ultimately knowing how cells communicate with each other will allow us to modify released bioactive mediators and/or create novel ways of altering the signal, which will lead to novel treatments for mucosal infection. PUBLIC HEALTH RELEVANCE: All cells can communicate with each other and their environment through channels within their outer membrane. This study seeks to understand if bacteria that cause disease in the tissue around the teeth hijack the communication between cells increasing inflammation and the severity of disease. Knowing how bacteria and cells communicate will allow us to create novel treatments for mucosal infections.